Scientific Name:
Nuttallovnis borealis
Nest Type: Cup
Nest Location: Coniferous
tree; 5-75'
Clutch Size: 3-4;
avg. 3
Food: Insects
Foraging Guild:
Hawks
This species is widely
distributed across the boreal zone throughout the forest zone of Canada,
extending into the Appalachian Mountains, northern Michigan, and northern
Minnesota (National Geographic Society 1983). The western portion of
the breeding range extends throughout the Rocky Mountain region to California
and northern Arizona and New Mexico. The species overwinters in Central
and South America and casually in southern California (Bent 1942, DeGraaf
et al. 1991). It migrates to Minnesota, arriving in early May, and migration
may last until mid-June. The species leaves the state beginning in early
August to late September (Janssen 1987).
The general breeding habitat
of the species consists of a variety of boreal forests including uplands,
lowlands, edges, beaver meadows, and recently logged and burned areas
(Roberts 1932, Green and Niemi 1978, Niemi and Pfannmuller 1979, Brewer
et al. 1991). However, the most important aspect needed by this species
and noted by all those above, is the presence of standing live or dead
trees from which the species forages for insects. Usually the species
can be seen at the top of these trees either singing or preparing to
forage in its typical flycatching fashion (Roberts 1932). The most commonly
used tree species are large pine, spruce, or tamarack. The species was
not found abundantly in many of the forested zones of the Chippewa and
Superior National Forests (Hanowski and Niemi 1991a, 1991b), nor is
very common in the large contiguous, black spruce or tamarack forests
of the Red Lake peatland (Niemi and Hanowski 1992).
The Olive-sided Flycatcher
nests on a horizontal conifer branch anywhere from 5 to 18 m in height
and generally away from the tree trunk. The species primarily forages
by hawking or flycatching for insects from the exposed perches of tall
dead standing trees (Green and Niemi 1977, DeGraaf et al. 199).
The status of the Olive-sided
Flycatcher in North America is emerging as a concern, based on its potential
decline on Breeding Bird Survey roadside counts (Sauer and Droege 1992).
A significant annual decline of 2.6 % in the eastern United States and
approaching a 6.1 % decrease has been noted across its range in North
America. In Minnesota, its trend has not been shown to be significantly
decreasing; however, the trend is negative at approximately 4 % per
year through 1989 (Janssen 1990) and - 3 % through 1990 (Collins et
al. 1992). Among the factors mentioned as possibly contributing to the
decline are (1) reductions in the availability of snags in suitable
habitat, (2) decreased populations of beaver, primarily in the northeastern
U.S., (3) suppression of forest fires, (4) loss of habitat to increased
urbanization, and (5) habitat changes in migration routes or on the
wintering grounds. Moreover, the species may require relatively large
blocks of boreal forest for breeding; at least 50 acres may be necessary
to support a single territorial pair.
Our observations indicate
that this species can tolerate disturbance such as logging and forest
fire, as long as some large dead and live trees are left standing. The
species can greatly benefit by leaving several tall trees and preferably
dead trees within these cut-over areas. Although quantitative information
is lacking, the Olive-sided Flycatcher tends to be found in a variety
of habitat types but generally in a landscape matrix with more coniferous
or boreal association rather than in a deciduous, dominated landscape.